I'm working on a die and am trying to extrude a rectangular shape to and irregular surface. The surface is concaved with a boss in the center. I've seen it done in solid works, but cannot figure out how to extrude to the required surface.
You can use the replace surface tool, which is buried in the offset tool.
Make your solid extrusion to some (any) blind depth. Pick the surface that you want to replace (the extruded face) so it highlights in pink, then hit Edit-->Offset.
When the offset dashboard appears, select the icon in the lower left corner of the screen (under the References tab) and change it to the last option (Replace Surface Feature). It will then ask you for a surface, at which point you should choose the surface you wanted to extrude to.
The result should be your extrude with the top die surface as per your requirement.